A total of 114 specimens of brown trout, Salmo trutta Linnaeus, 1758 was sampled by electrofishing between October 1998 and July 1999 from the Ceresone stream (North of Padua, Italy). Over 63% of fish were infected with 3 species of helminths: a tapeworm, Cyathocephalus truncatus (Pallas, 1781), and two acanthocephalan species, Echinorhynchus truttae (Schrank, 1788) and Acanthocephalus anguillae (Müller, 1780). On three occasions, in the fore-gut of 3 brown trout, 3 pairs of A. anguillae were found in copula. In all three cases, the male’s bursa was fully extruded and firmly attached to the posterior region of the female. Cement was found inside the bursa suggesting that insemination had probably occurred. Eight female A. anguillae recovered in five other infected trout had attached copulatory caps. Introduction The typical mating behavior in Acanthocephala may be deduced from Moniliformis moniliformis (= dubius) infections of laboratory rats (Nesheim et al. 1978; Crompton 1985); copulation among Acanthocephala has been observed rarely (Crompton 1985). Recently, a copulating pair of Dollfusentis heteracanthus was illustrated by Amin and Dailey (1996), and Richardson et al. (1997) published a paper on copulation and sexual congress of Leptorhynchoides thecatus in experimentally infected fish (Lepomis cyanellus). The copulatory pairs observed in this study were found in the formaldehyde-fixed alimentary canal of fish collected at mid-day. To the best of our knowledge, this is the first photographic documentation of acanthocephalans in copulation.
Copulation of Acanthocephalus anguillae (Acanthocephala)
SAYYAF DEZFULI, Bahram;
2000
Abstract
A total of 114 specimens of brown trout, Salmo trutta Linnaeus, 1758 was sampled by electrofishing between October 1998 and July 1999 from the Ceresone stream (North of Padua, Italy). Over 63% of fish were infected with 3 species of helminths: a tapeworm, Cyathocephalus truncatus (Pallas, 1781), and two acanthocephalan species, Echinorhynchus truttae (Schrank, 1788) and Acanthocephalus anguillae (Müller, 1780). On three occasions, in the fore-gut of 3 brown trout, 3 pairs of A. anguillae were found in copula. In all three cases, the male’s bursa was fully extruded and firmly attached to the posterior region of the female. Cement was found inside the bursa suggesting that insemination had probably occurred. Eight female A. anguillae recovered in five other infected trout had attached copulatory caps. Introduction The typical mating behavior in Acanthocephala may be deduced from Moniliformis moniliformis (= dubius) infections of laboratory rats (Nesheim et al. 1978; Crompton 1985); copulation among Acanthocephala has been observed rarely (Crompton 1985). Recently, a copulating pair of Dollfusentis heteracanthus was illustrated by Amin and Dailey (1996), and Richardson et al. (1997) published a paper on copulation and sexual congress of Leptorhynchoides thecatus in experimentally infected fish (Lepomis cyanellus). The copulatory pairs observed in this study were found in the formaldehyde-fixed alimentary canal of fish collected at mid-day. To the best of our knowledge, this is the first photographic documentation of acanthocephalans in copulation.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
